Continuity mistake: When he sends her the invitation for the christening, she opens and reads it and its on her desk when her boss walks in. When he's in, she picks it up and opens it again.
Factual error: There are two rentals cars driven by "Theresa" which have the same North Carolina license tag number, which is displayed on the front where required in Maine, the actual location of filming, but in North Carolina, license plates are not displayed on the front of the cars.
Continuity mistake: When Garret finds the messages and bottle in Theresa's bedside table, the candle on the table is lit in one shot, then unlit, and then lit again.
Continuity mistake: The state names on all the boats in the harbor have obviously been changed. The letters NC are a different size than the city name (New Harbor). This is because the movie was filmed in Maine and all the boats had to have temporary letters placed over the originals.
Continuity mistake: The scene where Garret and Theresa take the boat out for the early morning test sail. The wide shot cutaway as they are sailing out of the harbour has Theresa's left leg bent and laid flat against the boat. The immediate cut back to the two mid shot has Theresa with her left leg bent but lifted off the side of the boat. Pedantic but true.
Factual error: Throughout the movie we see several shots of the supposed NC coastline. None of NC's coastline contains giant pines on the beach or rocky cliffs at the water's edge nor does the coastline rise to over 12 ft above sea level for almost 30 miles inland (past the Outer Banks and the mainland sound shore).
Factual error: When Theresa is driving to meet Garret for the first time, there is an aerial shot of a suspension bridge. There are no vehicular suspension bridges in North Carolina. That particular bridge is located in Maine.
Continuity mistake: When Garret takes Theresa out sailing, he takes the ties off the mainsail, then the middle sail, but then the ties are back on the mainsail again.
Answer: None of the bottles ended up in Lake Michigan. Theresa is from Chicago, and when she and her son are at Boston Logan Airport she tells her ex-husband she'll be staying in Cape Cod for a few days, which is where she finds the bottle on the beach, along the Atlantic Coast. Then after the newspaper article, Theresa learns of another letter in a bottle, which Theresa notes as "bottle #2", and this bottle was found in Ocean City, Maryland, also along the Atlantic Coast. Catherine's letter in a bottle was found at Virginia's shoreline, so all of the bottles were found on the shores of the Atlantic Ocean.
Super Grover